
Description: Preview is a free and open-source document viewer application for macOS. It allows quick viewing of multiple file formats including images, PDFs, Markdown files, Office documents, and more. Preview has basic editing capabilities and annotation tools for PDFs.
Type: Open Source Test Automation Framework
Founded: 2011
Primary Use: Mobile app testing automation
Supported Platforms: iOS, Android, Windows

Description: Skim is a PDF reader and note-taking application for macOS. It provides annotations, highlighting, and notation tools for PDF documents, allowing users to mark up PDFs. Skim also enables searching PDF documents and works well with large PDF files.
Type: Cloud-based Test Automation Platform
Founded: 2015
Primary Use: Web, mobile, and API testing
Supported Platforms: Web, iOS, Android, API